Yes. If I play one game for long periods of time I get sick of it, thats why I'm mixing my gaming routine. I play Shadow complex for a bit, and then switch to Reach or BF 1943 for my multiplayer fix.

It kind of depends on the game I guess. For example, I'm trying to finally complete Infamous and so far, it's just a chore, which was part of the reason why I stopped playing it in the first place. More often than not though, I still have fun playing games.

I would not waste my time on a hobby that I didn't enjoy and it surprises me that others agree with the OP.  Why would you play something and not have fun playing it?  I get frustrated at times but only for brief moments and would never rage quit.

It's a hobby.

Well I've got Nintendo and Valve games so yes I'm having fun, if all I had was a PS3 or 360, I probably wouldn't since those consoles lack about 90% of the fun games out there, it's all about the old grind with them, online FPS titles, and multiplayer centric titles where you'll be left in the dust if you don't dedicate time and once you get there you've got a few matches that you enjoy stomping people till you get bored.

So basically if you're not having fun you should look at ways to diversify @OP I know you like Valve clearly, Portal 2 will be a saving grace when it has its major update this summer, otherwise I can reccomend Smash Bros Brawl, No More Heroes 1/2, SMG 1&2, Donkey Kong Country Returns, Zack and Wiki, 3D Dot Game Heroes, NSMB Wii, Wii Sports, Wii Sports Resort, Mario Kart DS, Kingdom Hearts Birth By Sleep, Super Meat Boy, Angry Birds, and Magicka.  All of these titles have given me hours upon hours of enjoyment and specifically fun times this generation.

I felt much the same way last gen however, Nintendo was trying to be like everyone else and not on their A game, other people were just trying to emulate each other, last gen it was GTA, now it's CoD, so really if you want to get out of the hum drum you just gotta look in places where you never looked before, which is why last gen I became a PC gamer and found titles like Starcraft and spent like 600 hours playing it and having fun

Why would I not be having fun?  The 3DS is out, I've got back into Monster Hunter and a remake of arguably the best game of all time is about to launch, among other things.

Usually the most fun video games are the ones with the best co-op options, splitscreen gaming options, and ability to create interaction in a room full of friends.

The most fun games I've played in the last 2 years:  Buzz! Monkey game for PS2, Just Dance, New Super Mario Bros. Wii, Rock Band (an absolute blast with 4 people playing at the same time), House of the Dead 2&3, Mad Dog McGree (a hilariously bad game, but total fun with 3 or 4 friends), Soul Calibur IV (so many hours spent playing with friends), Call of Duty Black Ops (has co-op online and local splitscreen so great fun with 3 or 4 people), Wii Sports Resort, and NBA Jam. 

I become bored when I try to play the games that other people say are great.  Just play the games you like.  Sitting in a room, by myself, and playing a 20-30 hour long game sounds miserable unless the game is a completely fun game. I personally can't play most RPGs because I would much rather just read a book than play through a game like that. 

i'm having fun, when people arent having fun and get easily frustrated playing games they should either quit or try another genre.

i think if people stop playing for a while though they'll be able to get back to it and rediscover the fun in playing.

if it wasnt fun for me i wouldnt spend money on it.

I'm having fun playing prototype.

i have no time to have fun!

i'm way to busy convincing the owners of the "other" consoles that they don't have fun!

well my point is that i wasn't having fun yet i was still pushing my self to do it. Tho this doesn't happen before, with so less time i have to game now i cherish each moment with great game of wide variety. but i am sure there are many gamers who dont game for fun especially on the online shooter space in games like COD.